Educate Yourself
About Grow Media (a.k.a. Substrates)
There are several types of Grow Media. The old standard, soil, is available, as well as Rockwool, Grow Rocks, Perlite & Vermiculite, Coir Fiber, and Rapid Rooters.
SOIL
Soil, the old bystander, has grown plants for eons. While just fine
for growing plants, the application of hydroponic technologies and substrates
can allow you full control of the growing environment. Nutrient solutions
do not leach beyond the root zone in a hydroponic system as they do in a
soil system. The control you have over the balance of the plant's environment
allows for a more specialized and scientific application of the things a
plant needs to grow. Readily available nutrients are more available to the
plants root zone, while the addition of lighting and Co2
allows for more complete metabolization of nutrients, water, air, light,
and Co2 to provide better and more exact growth rates, much bigger crop yields,
closer plant spacing, and more. Hydroponic crop production can exceed 20 times
the
amount of harvested crop than soil.
HYDROPONIC SUBSTRATES
There are several different types of major hydroponic growing
substrates. A growing substrate consists of an inert growing media that
is capable of holding water and air while physically supporting the root
zone. The root zone requires oxygen, water, and nutrients in the proper
balance
for
the plants to grow correctly. Without oxygen in the root zone they quickly
rot, and without water they will dry up and die quickly. Dependending upon
the hydroponic growing method used, one has various ways to control the
plants access to an aerated nutrient solution.
As a plant transpires, it utilizes water, air, light, and nutrients to grow. Depending upon the rate of transpiration you will need to pump the solution at a rate to match the plants utilization of these. Normally, with rockwool, you fill from the reservoir 2-5 times per day, however in certain environments with more heat or humidity, you may have to fill up to 20 times per day. The holding properties of substrates varies depending upon which substrate you use. It may require light experimentation to solidify your watering regimen.
ROCKWOOL
Rockwool is spun basalt rock fibers melted at a high temperature.
It has excellent water and oxygen retention properties. See Hydroponics
101 for more information about growing with Grodan Rockwool.
GROWROCKS (a.k.a Hydroton or Expanded Clay)
Grow Rocks have a highly porous quality that allows for excellent
water retention and air holding properties. An inert, sterile substrate,
grow rocks are excellent for many types of hydroponics systems. In addition
to having an attractive appearance they are also re-usable (sterilize after
each use). Grow rocks may be prone to eventual salt buildup, which will be
visible on the rocks and potentially at the base of the plants stem. If encrusted
with salt apply a leaching solution or use half strength nutrients with water
to leach the salts from the substrate.
PERLITE
Perlite, of volcanic origin, is a siliceous, sterile, spongelike,
amorphous glass mineral. Free draining with low water retention properties,
perlite is commonly mixed in a 1:1 ratio with vermiculite to create a substrate
that maintains the right amount of water while having good drainage.
VERMICULITE
Vermiculite is a porous, spongelike, sterile media. It’s lightweight
and has a high water absorption capacity- holding up to five times its weight
in water. It also has a relatively high cation exchange capacity, holding
nutrients in reserve and later releasing them. Care needs to be taken in
some systems when using vermiculite as a stand-alone since it is prone to
over saturation when nutrients are applied frequently, often resulting in
root rot.
COIR FIBER
Coir Fiber is an environmentally friendly, renewable resource, composed
of a byproduct of coconut harvesting. Coir fiber is highly porous to aid
in a strong root system. pH neutral, it has water retention capacities of
up to 88% and air-filled porosity values of 23%-29%.
RAPID ROOTERS
Rapid Rooters are a unique starter plug derived from naturally composted
tree bark. The air to water ratio within the plug matrix promotes root growth.
Vigorous roots make stronger plants.
